Composition comprising a phosphate binder and its preparation

ABSTRACT

An inorganic binder having calcium silicate sites which are connected the one with the other by alumina-silica phosphate bonds, whereby at least a portion of said alumina-silica bonds are alumina-silica phosphate bonds having a weight ratio Al 2 O 3 /SiO 2  ranging from 0.3:1 to 10:1, a weight ratio Al 2 O 3 /P 2 O 5  ranging from 0.0005 to 0.04, and a weight ratio P/B ranging from 20:1 to 100:1, whereby the inorganic binder further includes a waterproof and/or water repellent silicon compound or mixture.

FIELD OF THE INVENTION

The present invention relates to a composition comprising an inorganicbinder, most precisely to an inorganic phosphate binder.

THE PRIOR ART

Inorganic phosphate binder have already been proposed in the past.

For example in a previous patent application WO9903797 in the name ofMetal Chemical and Haji Anas, a polymeric matrix is disclosed, saidmatrix comprising a binder formed by mixing an alkali metal silicateaqueous solution with a powder comprising silico-aluminous reactive rawmaterials. A polymerization time of more than one hour is howevernecessary for reaching a sufficient hardening of the matrix.

It has also been proposed in U.S. Pat. No. 6,139,619 to form a binder bymixing a water soluble silicate with a water soluble amorphous inorganicphosphate glass in an aqueous medium. The hardening of the binderrequires the removal of water by a heat treatment.

In U.S. Pat. No. 4,375,551, an acid solution is prepared by mixingAl₂O₃.3H₂O with phosphoric acid, said acid solution being then mixedwith calcium silicate. The so obtained binder has after hardening poormechanical strength.

U.S. Pat. No. 4,504,555 discloses an inorganic resin formed by reactinga first liquid component containing a mono aluminum phosphate or a monomagnesium phosphate, with a second liquid component containing magnesiumoxide and/or wollastonite and a dispersing agent. Inert filler can beadded to the first or second component. The inert filler (particles notparticipating to the reaction) can be SiO2 particles. The productprepared by this reaction is a resin in which adjacent calcium silicatesites (wollastonite) bound by magnesium/aluminum phosphate bonds, not byalumina silica phosphate bonds.

U.S. Pat. No. 3,179,527 discloses a coating composition formulated byadding silica or lime to an acidic solution of aluminum phosphate.Calcium silicate is then added to the composition. As stated in column 2of said patent, the effect of added silica depends from the particlesize of the silica particles, fine silica particles forming open cracks,while coarser particles do not produce such cracks. The silica particlesare therefore not dissolved, otherwise the particle size of the silicaparticle would have no influence on cracks. The silica is therefore usedin this patent as filler. The use of silica in a prereacted compositionis even not indispensable according to said patent, as it could bereplaced by calcium silicate. Silica is therefore not participating inthe formation of bond between two adjacent calcium silicate particles.The compositions of this patent have a long shelf stability, meaningthat the hardening reaction is a slow process.

U.S. Pat. No. 3,923,525 discloses a foundry composition containing afoundry aggregate and a binder comprising a boron-containing aluminumphosphate, a material containing both an alkaline earth metal and anoxide, and water. As disclosed in said document, the preferred aluminumphosphates contain from 3 to 30 mole % of boron. The boron containingaluminum phosphates are prepared by reacting together the phosphoricacid or P₂O₅, alumina, and boric acid or boric oxide. The addition ofboric acid or boron additive is said to alter the reactivity of thealuminum phosphate with the alkaline earth material, especially forboron concentration above 10 mole % with respect to the moles ofaluminum. The preferred alkaline earth metal have a surface area of lessthan 8.5m²/g and are for example calcium silicate, calcium aluminate,magnesium silicate, etc. A particularly preferred calcium silicate iswollastonite with a calcium oxide to silica mole ratio equal to about 1.

When using reacting an acid alumina-silica phosphate solution having anAl₂O₃/SiO₂ weight ratio of about 0.5 and an Al₂O₃/P₂O₅ weight ratiogreater than 0.08, with calcium silicate or wollastonite, the initialsettling occurs in less than 10 minutes, meaning that the composition isnot suitable for coating fabrics in view of the substantially immediateincrease of viscosity. The reaction product is substantially no morefluid after less than about 4 minutes. Furthermore, the top coat of thelayer was provided with some white particles probably due to problem ofexcessive carbonation.

It has now been found that by using an acid alumina-silica phosphatecomposition comprising boric acid and specific additive, it was possibleto achieve an initial setting of more than 1 hour, advantageously morethan 2 hours, especially more than 4 hours by controlling Al₂O₃/P₂O₅weight ratio to less 0.04, while avoiding the carbonation problem or theproblem of formation of an upper coat of particles.

The present invention has for subject matter a binder composition with awork time of more than 20 minutes at 20° C. at atmospheric pressure (110⁵ Pa), and which can be adapted to the required work time, for exampleup to 6 hours or even more. Such a binder with long work time isadvantageous for ensuring a good coating of various support, especiallyfor having extremely thin coating layer.

The curing of the binder can however be accelerated by increasing thetemperature above 50° C., rendering therefor the coating process quiteeasy.

Furthermore, it has been observe that before hardening, liquidcomposition comprising the binder of the invention was quite homogeneousand stable. The homogeneity of the composition can be improved with aslow mixing, such as a slow paddle mixing.

These specific properties have been obtained by using specificadditives, and by using an acid alumina-boron-silica phosphate solutionhaving a P/B weight ratio from 20:1 to 100:1 and a Al₂O₃/P₂O₅ weightratio comprised between 0.0005 and 0.04.

Despite the fact that that U.S. Pat. No.3,923,525 teaches that boricacid alters the reaction of aluminum phosphate with the alkaline earthmaterial, the man skilled in the art was unable to predict that for acidalumina-silica phosphate solution, the reaction will only effectivelydelayed when having a large excess of phosphate with respect to alumina.

DESCRIPTION OF THE INVENTION The Binder

The invention relates to an inorganic binder having calcium silicatesites which are connected the one with the other by alumina-silicaphosphate bonds, whereby at least a portion of said alumina-silicaphosphate bonds are alumina-boron-silica phosphate bonds, the calciumsilicate sites acting as cross-linking sites for the alumina-silicaphosphate bonds, whereby said alumina-silicate phosphate bonds have:

a weight ratio Al₂O₃/SiO₂ ranging from 0.3:1 to 10:1, advantageouslyfrom 0.4:1 to 6:1, preferably between 0.5:1 and 2:1,

a weight ratio Al₂O₃/P₂O₅ ranging from 0.0005 to 0.04, advantageouslyfrom 0.0008 to 0.03, preferably from 0.001 to 0.02, and

a weight ratio P/B ranging from 20:1 to 100:1, advantageously from 21:1to 50:1, preferably from 22:1 to 30:1, and

whereby the inorganic binder further comprises a waterproof and/or waterrepellent silicon compound or mixture, the weight ratio waterproofand/or water repellent silicon compound or mixture/P+B being comprisedbetween 1:5000 and 1:10, advantageously between 1:1000 and 1:25,preferably between 1:500 and 1:75, and whereby at least a portion of thecalcium silicate sites are at least partly provided with a layer ofwaterproof and/or water repellent silicon compound or mixture.

Said organic binder is defined as being the reaction product obtained byreacting

an acid alumina-silica-boron phosphate solution having a pH of less than2, advantageously less than 1.5, preferably less than 1, said acidalumina-silica phosphate solution having:

a weight ratio Al₂O₃/SiO₂ ranging from 0.3:1 and 10:1, advantageouslyfrom 0.4:1 to 6:1, preferably between 0.5:1 and 2:1,

a weight ratio Al₂O₃/P₂O₅ ranging from 0.0005 to 0.04, advantageouslyfrom 0.0008 to 0.03, preferably from 0.001 to 0.02, and

a weight boron content such that the weight ration P/B is comprised from20:1 to 100:1, advantageously from 21:1 to 50:1, preferably from 22:1 to30:1,

with an amount of calcium silicate particles (advantageously such thatthe weight ratio calcium silicate site/SiO₂ present in thealumina-silica phosphate bonds is comprised between 1 and 1000,advantageously between 10 and 200, preferably between 20 and 100),

in presence of an amount of waterproof and/or water repellent siliconcompound or mixture such that the weight ratio waterproof and/or waterrepellent silicon compound or mixture/P+B being comprised between 1:5000and 1:10, advantageously between 1:1000 and 1:25, preferably between1:500 and 1:75, whereby said reaction is carried out optionally, butadvantageously, in presence of one or more inert fillers.

The acid alumina-silica phosphate solution, before addition of thecalcium silicate particles, has advantageously a low weight content incomponents selected from the group consisting of Fe, Ti, Zr, V, Cr, Mn,Zn, Na and mix thereof For example, the weight ratio components selectedfrom the group consisting of Fe, Ti, Zr, V, Cr, Mn, Zn, Na and mixthereof/Al₂O₃ is lower than 1, advantageously less than 0.1, preferablyless than 0.05.

Advantageously, the binder composition has a low weight content incomponents selected from the group consisting of Fe, Ti, Zr, V, Cr, Mn,Zn, Na and mix thereof, i.e. a weight ratio components selected from thegroup consisting of Na, Fe, Ti, Zr, V, Cr, Mn, Zn, and mix thereof/B ofless than 1, preferably less than 0.5, most preferably less than 0.2.

The calcium silicate site are preferably particles respondingsubstantially to the formula CaO.SiO₂ comprising a CaO weight content ofmore than 46%, a SiO₂ weight content of more than 52%, an Al₂O₃ weightcontent of more than 0.2%, a Fe₂O₃ weight content of less than 0.4%, aweight loss content when burned at 1000° C. of less than 0.5%.

Preferably at least 98% by weight, preferably at least 99% by weight ofthe binder is formed by the following atoms P, O, Si, Al, B and Ca.

Advantageously, substantially all alumina-silica sites are bound the oneto the other by alumina-boron-silica phosphate bonds.

The calcium silicate sites act preferably as cross-linking sites foralumina-boron-silica phosphate bonds.

According to an embodiment, the weight ratio calcium silicate site/SiO₂present in the alumina-silica phosphate bonds is comprised between 1 and1000, advantageously between 10 and 200, preferably between 20 and 100.

According to an advantageous embodiment, the calcium silicate sites arecalcium meta silicate sites having a substantially acicular nature witha length/diameter ratio from 2/1 to 50/1, advantageously from 3/1 to20/1, the calcium meta silicate sites having advantageously an averagelength from 10 μm to 10 mm, preferably from 50 μm to 5 mm.

According to a specific embodiment, the weight ratio calcium silicatesites/alumina-silica-boron phosphate bonds is comprised between 0.1 and1.1, advantageously between 0.3 and 0.9, preferably between 0.4 and 0.7.

Preferably, at least 50% by weight of the calcium silicate sites are atleast partly provided with a layer of waterproof and/or water repellentsilicon compound or mixture.

For example, calcium silicate sites are at least partly provided with alayer of waterproof and water repellent silicon compound or mixture,such as a layer of a fluoro silicon compound or mixture of suchcompounds.

Waterproof or water repellent silicon compound in the presentspecification refers to compounds suitable to make a coating or apartial coating which is water repellent or waterproof, said coatingbeing very thin and comprising silicon. Such a coating or partialcoating is achieved by using solvent based silicon solution and/orwater-base emulsion of silicon compound. Preferably, use is made of asolvent base solution (dispersible in water) of one or more of thefollowing silicon compounds: methylhydrogensilicone oil,dimethylsilicone oil, epoxy modified silicone oil, amino modifiedsilicone oil, polyether modified silicone oil, carboxyl modifiedsilicone oil, silanes (such as ether silanes, polyether silanes),siloxanes, silanols,

and/or a water-base emulsion of one or more of the following siliconcompounds: methylhydrogensilicone oil, dimethylsilicone oil, epoxymodified silicone oil, amino modified silicone oil, polyether modifiedsilicone oil, carboxyl modified silicone oil, silanes, siloxanes,silanols.

For example, silane-containing aqueous solutions that can providewater-repellent characteristics on the surface of a substrate have beendisclosed. See, e.g., U.S. Pat. Nos. 4,648,904, 4,757,106, 4,990,377,5,196,054, 5,550,184, and 5,664,014, European Patent 0 748 357, JapaneseKokai Patent Application No. Hei 11(1999)-181355, and US2003212196.

For example, U.S. Pat. No. 5,550,184 discloses reactive hydrolyzedsilane emulsions produced by emulsifying a hydrolyzable alkoxysilane inwater in the presence of a high HLB value emulsifier to simultaneouslyretain the hydrolyzable alkoxysilane in substantially totallyhydrolyzable state. The emulsion can produce durable coatings thatimpact water-repellent characteristics on a substrate.

The silicone and/or silane and/or siloxane partial coating of thecalcium silicate is for example by using a solvent basedsilicone/silane/siloxane solution and/or a solvent free aqueous siliconeand/or silane and/or siloxane emulsion or dispersion.

Water repellent compositions containing aqueous emulsions of silanes,siloxanes and silane/siloxanes for use on materials used in building tomake them water repellant are disclosed in WO9516752.

Solvent base composition suitable for rendering at least partly asubstrate (for example calcium silicate) water repellent is for exampledisclosed in WO 02/30848, U.S. Pat. No. 5,997,943, WO00/63129, U.S. Pat.No. 5,980,992, U.S. Pat. No. 5,415,927, EP548775, EP887394, etc.

Advantageously, the calcium silicate particles are only partly coated,for example from 5 to 75% of their surface.

According to an advantageous embodiment, the weight ratio waterproofand/or water repellent silicon compound or mixture / calcium silicate iscomprised between 1:10000 and 500:10000, advantageously between 5:10000and 200:10000, preferably between 10:10000 and 70:10000.

The binder of the invention is suitable for preparing product having alight weight (such a weight from 70 to 140 kg/m³) or a heavy weight(such as weight of 2,000 kg/m³ or even more). Products of the inventionhave high mechanical properties, such as compression strength of morethan 40N/mm², bending strength of more than 10 N/mm², etc.

The invention relates also to a composition and a product comprising atleast a binder according to the invention and at least one filler and/orreinforced material.

The invention relates also to composition comprising at least:

an inorganic binder according to the invention as disclosed here above,and

one or more fillers, advantageously at least a silicon containingfiller.

The compositions of the invention are composition before hardening,after hardening, possibly after an after treatment, such as a dryingstep, a heating step, etc.

Examples of fillers or reinforced materials which can be mixed with thebinder before its preparation, during its preparation, before itshardening or during its hardening are:

waste materials, such as finely divided waste material, for example fuelashes, fly ashes, buildings waste materials, etc.

flake-like materials such as mica, etc.,

silica sand, silica flour,

coloring agents or materials, such as inorganic coloring agents,pigments, etc.

cellulose and/or protein base fibers, such as natural fibers, flax,chip, straw, hemp, wool fibers, etc.

synthetic fibers, such as organic synthetic fibers, inorganic syntheticfibers, such as polyesters, polypropylene, glass and ceramic fibers,etc.

natural and synthetic organic base waste materials, such as saw dust,rice husk, straw and recycled organic waste,

natural fibers of mineral origin,

natural material, possibly treated (for example heat treated), such asperlite, vermiculite, etc.

mixtures of one or more of the above fillers.

Specific examples of possible fillers are:

rice husk,

waste recycle cardboard

shredded paper

rice husk/shredded paper composite

rice husk+waste recycle cardboard

pine needle

laminated elements, such as honeycomb board, normal cardboard, etc.

pigments

The filler or fillers are advantageously substantially not reactivefillers, preferably not reactive silicon containing fillers, i.e.fillers characterized in that less than 10% by weight, advantageouslyless than 5% by weight, preferably less than 1% by weight, mostpreferably less than 0.5% by weight, of the filler or silicon containingfillers are chemically reacted with the binder, for making for exampleone or more chemical bonds between filler and the binder.

Silica containing fibers are for example natural fibers, possiblytreated, synthetic fibers, mineral fibers, and mixtures thereof. Naturalfibers are preferred, such as wood fiber, straw fiber, rice husk or branfibers, mixtures thereof. The natural fibers are advantageously heattreated, for example at temperature higher than 400° C., such as at atemperature higher than 700° C. or 800° C., advantageously in anatmosphere rich in Nitrogen or in a nitrogen atmosphere. Said heattreatment is preferably carried after a drying step. Rice bran or ricehusk are preferred silica containing fibers used in the composition ofthe invention, said fibers being advantageously defatted and dried. Whensaid fibers are burned and carbonized in a nitrogen gas rice branceramic fiber are produced. Possibly some phenolic resin is added to therice bran or rice husk before the carbonizing and burning step. Possiblythe phenolic resin can be mixed with rice bran so as to prepare or formrice bran containing fibers or filaments, the latter fibers or filamentafter drying being carbonized and burnt (for example at a temperature of300 to 1100° C. during a time sufficient for the formation of ceramics).The silica containing fibers are advantageously ceramic silicacontaining fibers, basalt containing fibers, carbon containing fibers,combinations thereof. Such fibers, especially rice bran ceramic fibers,have a high strength, a high hardness, a low density, a low friction(hereby the fibers can easily flow the one with respect to the other,whereby facilitating the mixing step).

Additives can be added to the binder before its preparation, during itspreparation, before its hardening or during its hardening, suchadditives are for example:

foaming agents, such as water peroxide, organic peroxide, etc.

viscosity regulating agents, such as superplasticizer

material for improving the impermeability or the water repulsion such aslignosulfonates and silica fume

penetrating agents

dispersing agents

mixtures thereof

The filler comprises advantageously silicon containing fibers with aweight average length of less than 1000 μm, advantageously comprisedbetween 25 μm and 300 μm, preferably comprised between 50 μm and 250 μm.

For example, the composition comprises silicon containing fibers with alength of less than 1000 μm, the weight content of silicon containingfibers with a length of less than 1000 μm in the composition after itshardening and after removal of the possible free water being of at least0.5%.

For example, the weight ratio calcium silicate particles/liquid acidalumina-boron-silica phosphate solution of the composition before itshardening, preferably before its setting is comprised between 0.1 and10, preferably from 0.2 and 5, most preferably between 0.4 and 2.

According to a preferred embodiment, the silicon containing fibers witha length of less than 1000 μm are substantially not reactive with thebinder.

According to a further advantageous embodiment, after hardening andremoval of free water (free water is water present in the composition,such as in the hardened composition, but which can be removed in adrying step at a temperature of 100° C.), the composition comprises from1% up to 85% by weight, advantageously from 2% to 75% by weight,preferably from 20% to 65% by weight, most preferably from 30% to 60% byweight silicon containing fibers with a length of less than 1000 μm,advantageously less than 500 μm, which are substantially not reactivewith the binder.

The silica containing fillers, especially fibers, are advantageouslytreated with a water repellent agent, such as a water repellent coatingof less than 10 μm. This coating is for example a fluoro silane coating.

It has been observed that the presence of at least 0.5% by weight,preferably at least 1% by weight of silicon containing fibers,advantageously silicon containing fibers non reactive with the binder orsubstantially non reactive with the binder, it was possible to preventthe formation of any cracks at the surface of the hardened composition,as well as advantageously in the body of the hardened composition, evenif the hardened composition has a high thickness, such as a thickness ofmore than 2 mm, advantageously of more than 5 mm, such as a thicknesscomprised between 10 mm and 50 mm.

According to a further detail, the composition further comprises silicaflour with a particle size of less than 500 μm, advantageously comprisedbetween 2 and 400 μm, preferably comprised between 2 and 100 μm, mostpreferably between 5 and 60 μm, the weight content of silica flour inthe composition after its hardening and after removal of the possiblefree water being of at least 0.5%, advantageously comprised between 1and 10%, preferably comprised between 2 and 8%.

For example, the silica flour has an average (in weight) particle sizecomprised between 10 and 50 μm, the weight content of silica flour inthe composition after its hardening and after removal of the possiblefree water being comprised between 2 and 8%.

According to a further advantageous detail, the composition furthercomprises crystallized alumina silicate particles which aresubstantially not reactive with the binder and which have an average (inweight) particle size comprised between 5 and 100 μm, the weight contentof non reactive crystallized alumina silicate in the composition afterits hardening and after removal of the possible free water beingcomprised between 1 and 10%.

The composition, as well as the binder of the invention can be used forattaching two elements together, i.e. as glue, heat resistant glue orsealant or for manufacturing products with various shapes.

The binder /composition of the invention is suitable for preparingproduct having a light weight (such a weight from 70 to 140 kg/m³) or aheavy weight (such as weight of 2,000 kg/m³ or even more), depending tothe addition of fillers, additives, etc., such as foaming agents.

Products of the invention have high mechanical properties, such as oneor more of the following properties (preferably several of saidproperties): compression strength of more than 40N/mm², bending strengthof more than 10 N/mm², very low heat of combustion (less than 500 KJ/kg,advantageously less than 100 KJ/kg, method used: ASTM D 2015 and BS ENISO 1716), a high modulus of rupture (such as more than 10 MPa, forexample between 12 and 20 MPa, method of analysis: NBN EN 196-1), a highcompressive strength (more than 50 MPa, such as from 70 to 100 MPa,method of analysis: NBN EN 196-1), a high Young's modulus (more than5000 MPa, such as between 8000 and 15000 MPa, method of analysis: NBN EN196-1), absence o swelling even for water absorption from 10% up to 30%depending of the porosity, etc.

Products of the invention can be used as insulating materials (aspanels, sheets, granules, etc), fire protection material, heatprotection material, chemical protection material, buildings material(such as bricks, concrete, etc.), for making molds, shaping, casting andmoldings products, tiles, roofing sheet, coating layers, inner layer,laminated products, metallic profile, aluminum profile, steel profile,metal band or plate, flexible membrane, polyethylene web. Polymer layer(polyurethane, latex, etc.), etc. Specific examples are: roofing sheet,insulation panels, coating surface material

Wear resistant tile, high strength building elements, fire and heatresistant elements, adhesive material, sealants, slates, laminatedelements, joint compounds, refractory, mineral fibers, etc.

The invention relates also more precisely to a product made at leastpartly or associated at least partly to a hardened composition of theinvention, as disclosed here above. For example the product can be asupport provided with a coating layer with a thickness for example of 1to 10 mm, or even more.

The product can also have the form of a laminated product, an innerlayer being made from a composition of the invention, said inner layerhaving for example a thickness of 5 mm up to 100 mm, or even more.

According to an embodiment, the hardened layer covers at least partly aface of a support element. One or more faces of the support can beprovided with a hardened layer. The thickness of the layer isadvantageously lower than 10 mm, such as lower than 5 mm, such as 4 mm,3 mm, 2 mm, 1 mm, 500 μm, 250 μm, 100 μm, depending on the propertieswhich are required.

According to an advantageous embodiment, the hardened layer covers atleast partly a face of a support comprising a core which can besubjected to a water swelling. It has been observed that by coatingalready one face of a plate (which can be subjected to a water swelling)with a composition of the invention, it was possible to obtain afterhardening of the composition, a product which has a reduced swellingeven after being dipped in water for 72 hours at 20° C. Tests made oncommercial wood fiber composite material with a swelling of 37% afterbeing dipped in water for 72 hours at 20° C., have shown that byproviding one or more faces of the material with a thin hardened layerof the composition of the invention, it was possible to reduce theswelling to less than 10%, advantageously less than 6%, preferably lessthan 2%.

According to a specific embodiment, at least partly a face not coveredby a hardened layer of the invention is provided with a water repellentcoating, advantageously silicon containing water repellent coating, suchas a fluoro silicon coating (fluoro silane, etc. such as fluorosilanemarketed by 3M as water repellent agent, such as the productScotchgard®).

The thickness of the water repellent coating is advantageously less than500 μm, such as less than 250 μm, preferably less than 150 μm, mostpreferably less than 100 μm, for example less than 50 μm, or evenlesser, such as less than 20 μm or even less than 10 μm.

According to a more specific embodiment, substantially all the faces notcovered with the hardened layer are provided with a water repellentcoating.

According to an embodiment, the support has two substantially parallelfaces (top and bottom faces or major faces, front and rear faces)connected the one to the other by lateral faces, whereby said lateralfaces (bottom/top or front/rear faces) have a higher water permeabilitythan the two substantially parallel faces. In said embodiment, thelateral faces of the support are provided with a water repellentcoating. The water repellent coating on said lateral faces covers alsoat least a portion of the front/rear faces along their edges or at leasta portion of the hardened layer adjacent to the edges of said front andrear faces. The water repellent coating can be carried out before and/orafter providing the support with the hardened layer of the invention.

The invention further relates also to a product comprising a supporthaving at least one face at least partly coated with a compositionaccording to the invention, as disclosed here above.

Advantageously, the hardened layer covers at least partly a face of asupport comprising a core which can be subjected to a water swelling,whereby at least partly a face not covered by hardened layer is providedwith a water repellent coating.

The water repellent coating is advantageously a silicon containing waterrepellent coating.

According to an embodiment, the support is a fabric, advantageously aglass fabric with a weight from 50 g/m² to 500 g/m², at least one facethereof being at least partly coated with a layer of a compositionaccording to anyone of the claims 9 to 16, said layer having an averagethickness of less than 500 μm, advantageously comprised between 50 μmand 250 μm.

The invention further relates to a process for the preparation of aninorganic binder having calcium silicate sites which are connected theone with the other by alumina-silica phosphate bonds, the calciumsilicate sites acting as cross-linking sites for the alumina-silicaphosphate bonds with a weight ratio Al₂O ₃/SiO₂ ranging from 0.3:1 and10:1,

* in which water insoluble calcium silicate particles, possibly partlycoated with a waterproof and/or water repellent silicon compound ormixture, are mixed with an acid alumina-silica phosphate solutioncomprising boric acid and waterproof and/or water repellent siliconcompound or mixture, at a temperature lower than 70° C., advantageouslylower than 50° C., said acid alumina-silica phosphate solutioncomprising solubilized SiO₂ and having a pH of less than 2,advantageously less than 1.5, preferably less than 1, said acidalumina-silica phosphate solution having:

a weight ratio Al₂O₃/SiO₂ ranging from 0.3:1 and 10:1, advantageouslyfrom 0.4:1 to 6:1, preferably between 0.5:1 and 2:1,

a weight ratio Al₂O₃/P₂O₅ ranging from 0.0005 to 0.04, advantageouslyfrom 0.0008 to 0.03, preferably from 0.001 to 0.02, and

a weight boron content such that the weight ration P/B is comprised from20:1 to 100:1, advantageously from 21:1 to 50:1, preferably from 22:1 to30:1, and said acid alumina-silica phosphate comprising an amount ofwaterproof and/or water repellent osilicon compound or mixture such thatthe weight ratio waterproof and/or water repellent silicon compound ormixture/P+B being comprised between 1:5000 and 1:10, advantageouslybetween 1:1000 and 1:25, preferably between 1:500 and 1:75, and wherebyat least a portion of the calcium silicate sites are at least partlyprovided with a layer of waterproof and/or water repellent siliconcompound or mixture, or

* in which water insoluble calcium silicate particles partly coated witha layer of waterproof and/or water repellent silicon compound or mixtureare mixed with an acid alumina-silica phosphate solution comprisingboric acid and possibly waterproof and/or water repellent siliconcompound or mixture, at a temperature lower than 70° C., advantageouslylower than 50° C., said acid alumina-silica phosphate solutioncomprising solubilized SiO₂ and having a pH of less than 2,advantageously less than 1.5, preferably less than 1, said acidalumina-boron-silica phosphate solution having:

a weight ratio Al₂O₃/SiO₂ ranging from 0.3:1 and 10:1, advantageouslyfrom 0.4:1 to 6:1, preferably between 0.5:1 and 2:1,

a weight ratio Al₂O₃/P₂O₅ ranging from 0.0005 to 0.04, advantageouslyfrom 0.0008 to 0.03, preferably from 0.001 to 0.02, and

a weight boron content such that the weight ration P/B is comprised from20:1 to 100:1, advantageously from 21:1 to 50:1, preferably from 22:1 to30:1, and whereby the amount of waterproof and/or water repellentsilicon compound or mixture coating the water insoluble calcium silicateparticles, possibly with the waterproof and/or water repellent siliconcompound or mixture present in the solution is such that the weightratio waterproof and/or water repellent organic silicone and/or silaneand/or siloxane/P+B being comprised between 1:5000 and 1:10,advantageously between 1:1000 and 1:25, preferably between 1:500 and1:75, and whereby at least a portion of the calcium silicate sites areat least partly provided with a layer of waterproof and/or waterrepellent silicon compound or mixture.

The acid pH of the acid alumina-boron-silica-phosphate solution isadvantageously obtained by using phosphoric acid or an acid mixturecontaining at least phosphoric acid and boric acid. Preferably,substantially only a mix of phosphoric acid and boric acid is used asmineral acid, most preferably as acids for lowering the pH of thesolution to less than 2.

Advantageously, at least one filler is added to the binder before itshardening or to the reacting solution for making a binder or to thecalcium silicate to be reacted with the acid alumina-silica-phosphatesolution or to the acid alumina-silica-phosphate solution before addingthe calcium silicate particles.

According to various embodiments, the compounds used in the preparationprocess are used in an amount adapted for the preparation of a binder orcomposition of the invention with one or more specific characteristicsor details.

Advantageously, the hardening of the binder is carried out at atemperature comprised between 0° C. and 50° C., optionally underpressure.

According to a detail, the amount of calcium silicate added to the acidsilica alumina phosphate solution is such that the weight ratio calciumsilicate/SiO₂ present in the acid solution is comprised between 1 and 5,advantageously comprised between 1.5 and 3.5, preferably between 2 and3.

According to a further detail of an embodiment, the acid silica aluminaphosphate solution is prepared by mixing a silica - alumina mixture withan acid mixture consisting substantially only of phosphoric acid andboric acid, with a weight ratio P/B ranging from 20:1 to 100:1,advantageously from 21:1 to 50:1, preferably from 22:1 to 30:1.

According to still a further detail, the acid silica alumina phosphatesolution is prepared by mixing a silica - alumina mixture with a boronsalt and an acid selected from the group consisting of phosphoric acidand a mix of phosphoric acid and boric acid, whereby the weight ratioP/B of the so prepared acid alumina phosphate solution ranges from 20:1to 100:1, advantageously from 21:1 to 50:1, preferably from 22:1 to30:1.

According to a further detail, the acid silica alumina phosphatesolution is prepared by mixing silica particles with an acid consistingsubstantially only of phosphoric acid or of a mixture of phosphoric acidand boric acid, and by mixing thereafter said particles to the acidsilica containing solution alumina particles.

In the process of the invention, a filler and/or a reinforced materialis advantageously mixed with the calcium silicate particles before beingmixed with the acid alumina-silica phosphate solution and/or a fillerand/or a reinforced material is mixed to the mixture calciumsilicate/alumina—silica phosphate solution, before or during itshardening.

The binder of the invention is prepared by using an acid alumina-silicaphosphate solution, said solution is advantageously prepared by reactingaluminum oxide powder (size advantageously lower than 50 μm, preferablylower than 30 μm, for example from 5 to 25 μm) with a purity of morethan 95%, preferably more than 99%, silica powder (size advantageouslylower than 50 μm, preferably lower than 30 μm, for example from 10 to 25μm) with a purity of more than 95%, preferably of more than 99%, andphosphoric acid as an aqueous phosphoric acid or in presence of anaqueous medium. The phosphoric acid has preferably a purity of more than95%, most preferably of more than 99%. Phosphoric acid is available invarious concentration. Preferably, the phosphoric acid will be aphosphoric aqueous solution with a phosphoric acid concentration of morethan 75%, preferably of more than 85%. Preferably, the silica powder isfirst mixed with the phosphoric acid and then the alumina particles areadded.

The acid alumina-silica phosphate solution contains possibly some otheracids, such as organic acid, strong mineral acid, etc, however, in thiscase, the content of such acid will preferably be less than 10% of thephosphoric acid and boric acid content of the solution.

Instead of using aluminum oxide, it is possible to use aluminumphosphate, aluminum hydroxide, etc. However, aluminum oxide ispreferred.

Instead of using silica, preferably precipitated silica particles, it ispossible to use waste material issuing from glass bottles.

Possibly the aqueous phosphoric acid solution contains other solvents,such as alcohol, etc.

When a foamed product is desired, more water or solvent will be used fordecreasing as much as possible the viscosity.

The acid alumina-boron-silica phosphate solution has advantageously a pHlower than 2, preferably lower than 1.

The acid alumina-boron-silica phosphate solution is advantageouslyfiltered so as to remove possibly not dissolved particles.

It has been observed that when using silica particles for thepreparation of the acid alumina-boron-phosphate solution with a pH lowerthan 2, most preferably lower than 1, the dissolution of aluminaparticles was improved. The presence of solubilized SiO₂ in the acidsolution was also improving the formation of the bonds when adding thewater insoluble calcium silicate particles. Even, if some calciumsilicate particles are solubilized due to the low pH, some calciumsilicate particles remains insoluble, due for example to the increase ofpH to a value comprised between 3 and 6.

According to a specific embodiment, the process for the preparation of acomposition according to the invention is a process, in which a bindingmixture is prepared by mixing water insoluble calcium silicate particleswith an acid alumina-silica phosphate solution at a temperature lowerthan 50° C., said acid alumina-silica phosphate solution comprisingsolubilized SiO₂ and having a pH less than 2, advantageously less than1.5, preferably comprised between 0.5 and 1.5, said alumina-boron-silicaphosphate solution having a weight ratio Al₂O₃/SiO₂ rangingadvantageously from 0.3:1 and 10:1, preferably from 0.6:1 and 6:1, inwhich silicon containing fibers with a length of less than 1000 μm aremixed with water insoluble calcium silicate particles, prior to orduring the mixing of water insoluble silicate particles with an acidalumina-silica phosphate solution and/or in which silicon containingfibers with a length of less than 1000 μm are mixed with the bindingmixture before its complete hardening.

Preferably, the binding mixture is first prepared and then the siliconcontaining fibers are added. Said addition is carried out when thebinding mixture is still sufficiently liquid or pourable by gravity.Possibly before and/or during the addition of the fibers, water can beadded for controlling the viscosity. Possibly the silicon containingfibers are prewetted before being added to the binding mixture.

According to an advantageous embodiment, silica flour is added to thewater insoluble calcium silicate particles, prior to or during themixing of water insoluble silicate particles with an acid alumina-silicaphosphate solution and/or to the binding mixture before its completehardening, said addition being carried out prior, during or after theaddition of silicon containing fibers.

Preferably, the silicon containing fibers and the silica flour arepremixed before being added to the acid alumina-boron-silica phosphatesolution or to the binding mixture.

According to a possible embodiment, the insoluble calcium silicateparticles, the silicon containing fibers and the silica flour arepremixed before being added to and mixed with the acidalumina-boron-silica phosphate solution.

Advantageously, the weight ratio water insoluble calcium silicateparticles/solubilized SiO₂ present in the alumina-silica phosphatesolution is greater than 10, preferably greater than 20.

Preferably, the hardening of the binder/composition is carried out at atemperature comprised between 0° C. and 50° C., such as advantageouslybetween 10 and 30° C. Higher temperature can be applied for initiatingthe reaction and/or for speeding the hardening.

The binder/composition is preferably hardened under pressure, such asunder a pressure comprised between 2 10⁵ Pa and 100 10⁵ Pa, for example5 10⁵ Pa, 10⁶ Pa, 2 10⁶ Pa, etc. When making thin coating layer on asupport, such as a fabric, a glass fabric, fiber mat, a mat of glassfibres, etc. the hardening can be carried out between two movingsupports, such as transport bands.

The amount of calcium silicate added to the acidsilica-boron-alumina-phosphate solution is advantageously such that theweight ratio calcium silicate/SiO₂ present in the acid solution iscomprised between 10 and 1000, advantageously comprised between 20 and500.

According to a preferred embodiment, the silica used for the preparationof the acid silica alumina-boron-phosphate solution is precipitatedsilica.

The acid alumina-silca solution before its mixing with insoluble calciumsilicate particles has advantageously a pH of less than 2, preferablyless than 1.5, for example comprised between 0.1 and 1.5, preferablycomprised between 0.5 and 1.5. The acid pH is advantageously obtained byusing phosphoric acid or an acid mixture containing at least phosphoricacid and boric acid. Preferably, substantially only phosphoric acid,possibly with boric acid is used as mineral acid, most preferably asacid for lowering the pH of the solution to less than 2.

The calcium silicate particles are advantageously calcium meta silicateparticles having a substantially acicular nature with a length/diameterratio from 2/1 to 50/1, advantageously from 3/1 to 20/1.

The calcium meta silicate particles have preferably an average lengthfrom 10 μm to 10 mm, advantageously from 50 μm to 5 mm.

According to a preferred embodiment, the calcium silicate particles actas cross-linking sites for alumina-silica phosphate bonds. It seems alsothat the presence of insoluble calcium silicate particles catalyzes theformation of alumina-silica phosphate bonds.

The calcium silicate particles are advantageously at least partly coatedwith a water repellent layer or a waterproof layer, advantageously awater proof layer of silicon compound or mixture or a water repellentlayer of silicon compound or mixture, said very thin layer coating forexample only a portion of the calcium silicate particles.

In the process of the invention, the alumina-silica phosphate solutionhas advantageously a weight ratio Al₂O₃/SiO₂ ranging from 0.3:1 and10:1, preferably from 0.6:1 and 6:1.

For example, the weight ratio calcium silicateparticles/alumina-silica-boron phosphate solution is comprised between0.1 and 10, preferably from 0.2 and 5, most preferably between 0.4 and2.

In the process of the invention, various filler and/or a reinforcedmaterial can be mixed with the calcium silicate particles before beingmixed with the acid alumina-silica phosphate solution, and/or a fillerand/or a reinforced material is mixed to the mixture calciumsilicate/alumina—silica phosphate solution, before its or during itshardening.

Examples of fillers or reinforced materials which can be mixed with thebinder before its preparation, during its preparation, before itshardening or during its hardening are:

waste materials, such as finely divided waste material, for example fuelashes, fly ashes, buildings waste materials, etc.

flake-like materials such as mica, etc.,

silica sand, silica flour,

coloring agents or materials, such as inorganic coloring agents,pigments, etc.

cellulose and/or protein base fibers, such as natural fibers, flax,chip, straw, hemp, wool fibers, etc.

synthetic fibers, such as organic synthetic fibers, inorganic syntheticfibers, such as polyesters, polypropylene, glass and ceramic fibers,etc.

natural and synthetic organic base waste materials, such as saw dust,rice husk, straw and recycled organic waste,

natural fibers of mineral origin,

natural material, possibly treated (for example heat treated), such asperlite, vermiculite, etc.

basalt containing fibers, carbon containing fibers, etc.

combinations thereof

.etc.

Additives can be added to the binder/composition before its preparation,during its preparation, before its hardening or during its hardening,such additives are for example (examples given as example only):

foaming agents, such as water peroxide, organic peroxide, etc.

viscosity regulating agent, such as superplasticizer

material for improving the impermeability or the water repulsion such aslignosulfonates

silica fume

penetrating agents,

suspension agents,

mixtures thereof.

Possibly, additives or fillers can be added during or after thehardening, for example for making a top coat.

The binder/composition of the invention is prepared by using an acidalumina-silica phosphate solution, said solution is advantageouslyprepared by reacting aluminum oxide powder (size advantageously lowerthan 50 μm, preferably lower than 30 μm, for example from 5 to 25 μm)with a purity of more than 95%, preferably more than 99%, silica powder(size advantageously lower than 50 μm, preferably lower than 30 μm, forexample from 10 to 25 μm) with a purity of more than 95%, preferably ofmore than 99%, and phosphoric acid as an aqueous phosphoric acid or inpresence of an aqueous medium. The phosphoric acid has preferably apurity of more than 95%, most preferably of more than 99%. Phosphoricacid is available in various concentration. Preferably, the phosphoricacid will be a phosphoric aqueous solution with a phosphoric acidconcentration of more than 75%, preferably of more than 85%. Preferably,the silica powder is first mixed with the phosphoric acid and then thealumina particles are added.

The acid alumina-silica phosphate solution contains possibly some otheracids, such as organic acid, strong mineral acid, etc, however, in thiscase, the content of such acid will preferably be less than 10% of thephosphoric acid content of the solution.

Instead of using aluminum oxide, it is possible to use aluminumphosphate, aluminum hydroxide, etc. However, aluminum oxide ispreferred.

Instead of using silica, preferably precipitated silica particles, it ispossible to use waste material issuing from glass bottles.

Possibly the aqueous phosphoric acid solution contains other solvents,such as alcohol, etc.

When a foamed product is desired, more water or solvent will be used fordecreasing as much as possible the viscosity. It is also possible toobtain a foaming product by applying the acid composition on a basecontaining support or on an alkaline support.

The acid alumina silica-boron-phosphate solution has advantageously a pHlower than 2, preferably lower than 1.

It has been observed that when using silica particles for thepreparation of the acid alumina-boron-phosphate solution with a pH lowerthan 2, most preferably lower than 1, the dissolution of aluminaparticles was improved. The presence of solubilized SiO₂ in the acidsolution was also improving the formation of the bonds when adding thewater insoluble calcium silicate particles. Even, if some calciumsilicate particles are solubilized due to the low pH, some calciumsilicate particles remains insoluble, due for example to the increase ofpH to a value comprised between 3 and 6.

EXAMPLES

Details and characteristics of the invention will appear from thedescription of the following examples.

In said examples, the following products have been used:

WATER: water with a low calcium/magnesium content (less than 100 ppm)

SiO₂: precipitated SiO₂ particles with an average size of 10-15μm—purity of 99%

Al₂O₃: powder with an average particle size of 10-15 μm—purity of 99%

Phosphoric acid P1: aqueous solution containing 90% by weight phosphoricacid

Phosphoric acid P2: aqueous solution containing 75% by weight phosphoricacid.

Calcium silicate: calcium meta silicate powder, water insoluble,acicular nature, length of 1 mm, diameter 100 μm.

Rice Husk fibers (RHF1): dried natural fibers (water content less than2%) with an average (in weight) length of about 100 μm.

Rice Husk fibers (RHF2): dried natural fibers (water content less than2%) with an average (in weight) length of about 200 μm.

Rice bran ceramic fiber (RBCF1): defatted bran mixed with phenolicresin, shaped in filament, dried and carbonized and burnt under nitrogenatmosphere at 800° C., the fibers having a length of about 100 μm.

Rice bran ceramic particles (RBC): defatted bran mixed with phenolicresin, powdered, dried and carbonized and burnt under nitrogenatmosphere at 800° C., the powder having an average particle size(average in weight) of about 50 μm.

Crystallized alumina silicate (CAS): not reactive with the phosphatesolution, the particles having an average particle size of 50 μm(average in weight).

Silica Flour (SF): average (in weight) particle size of about 30 μm

Silica fume (Sf): average (in weight) particle size 50 μm.

Glass fiber (GF): glass fibres with a length of 50 μm to 250 μm, whichhave been treated with a water repellent agent (fluoro silane)

Basalt fiber (BF): Basalt fiber with a length of 50 μm to 250 μm

Carbon fibers (CF): Carbon fibers with a length of 50 μm to 250 μm

Water repellent silane/siloxane WRS1: a liquid solvent free aqueousbased silane/siloxane solution containing 1.5% by weight silane/siloxaneprepared from Dow Corning® 520 Dilutable water repellent emulsion

Water repellent silane/siloxane WRS2: a low VOC aqueous silicone waterrepellent composition diluted with water so as to contain 1.5% by weightsilicone compound (prepared from the composition Dow Corning® IE-6694)

Water repellent fluoro silane WRS3: an ethanol composition comprising1.5% by weight of silane ether of the formulaCF₃—(CF₂)₇—(CH2)₂—Si—(OCH₃)₃

Examples of Binders

The binders have been prepared by adding SiO₂ particles to phosphoricacid. After dissolution of the SiO₂ particles, Al₂O₃ particles wereadded. An acid alumina silica phosphate aqueous solution was soprepared. Thereafter boric acid was added and optionally water repellentcomposition was further added. The pH of said acid solution was thenmeasured at 20° C. Possibly some water was added.

To said acid solution, calcium silicate particles was added. Beforehardening of the composition of the invention, the composition wasfluid. After the addition of calcium silicate particles, the hardeningof the binder can be started, but said starting could be delayed at roomtemperature, and even better at temperature from 0° C. to 10° C. Saidhardening can however be accelerated at temperature higher than about50° C. In order to control the viscosity of the mixture, water can beadded. The initial setting time of the composition at room temperaturewas measured, said initial setting time could be considered as the timerequired for the start of the hardening reaction.

In some tests, the calcium silicate particles were first treated withthe water repellent composition, before being added to the acidalumina-boron-silica phosphate solution.

The initial setting of the binder has been measured.

The following tables give the composition of the binders prepared.

TABLE 1 comparative comparative Binder 1 2 3 4 5 6 SiO₂ (g) 0.15 1.457.25 8.7 1 1 Al₂O₃ (g) 0.08 0.8 4 4.6 0.53 0.53 Phosphoric acid 99% (g)75 74 59 56 75 75 boric acid (g) 6 6 6 6 6 4 water (ml) 25 25 25 25 3015 WRS1 (g) 15 15 15 15 10 25 SiO₂/P₂O₅ 0.002 0.018 0.158 0.198 0.0180.018 Al₂O₃/SiO₂ 0.53 0.53 0.53 0.53 0.53 0.53 Al₂O₃/P₂O₅ 0.001 0.010.084 0.105 0.01 0.01 P/B 24 23 18 17.6 24 36 Calcium silicate (g) 60 6060 60 60 60 pH of the acid solution <1 <1 <1 <1 <1 <1 initial settingtime (hour) >40 >3 <0.2 <0.2 >20 >40 WRS/P + B 0.01 0.01 0.012 0.0120.006 0.015 The ratio P/B, SiO₂/P₂O₅, Al₂O₃/SiO₂, Al₂O_(3/)P₂O₅ areweight ratio for the acid solution (before addition of the calciumsilicate particles). WRS1 is the amount in gram of water repellentsolution including the water present WRS/P + B is the weight ratiobetween the water repellent silicon compound (i.e. the active agentpresent in the solution) and the sum of phosphorus and boron present inthe solution.

TABLE 2 comparative comparative Binder 7 8 9 10 11 12 SiO₂ (g) 0.15 1.457.25 8.7 1 1 Al₂O₃ (g) 0.08 0.8 4 4.6 0.53 0.53 Phosphoric acid 99% (g)75 74 59 56 75 75 boric acid (g) 6 6 6 6 6 4 water (ml) 25 25 25 25 3015 WRS2 (g) 15 15 15 15 10 25 SiO₂/P₂O₅ 0.002 0.018 0.158 0.198 0.0180.018 Al₂O₃/SiO₂ 0.53 0.53 0.53 0.53 0.53 0.53 Al₂O₃/P₂O₅ 0.001 0.010.084 0.105 0.01 0.01 P/B 24 23 18 17.6 24 36 Calcium silicate (g) 60 6060 60 60 60 pH of the acid solution <1 <1 <1 <1 <1 <1 initial settingtime (hour) >40 >3 <0.2 <0.2 >20 >40 WRS/P + B 0.01 0.01 0.012 0.0120.006 0.015 The ratio P/B, SiO₂/P₂O₅, Al₂O₃/SiO₂, Al₂O₃/P₂O₅ are weightratio for the acid solution (before addition of the calcium silicateparticles). WRS2 is the amount in gram of water repellent solutionincluding the water present WRS/P + B is the weight ratio between thewater repellent silicon compound (i.e. the active agent present in thesolution) and the sum of phosphorus and boron present in the solution.

TABLE 3 comparative comparative Binder 13 14 15 16 17 18 SiO₂ (g) 0.151.45 7.25 8.7 1 1 Al₂O₃ (g) 0.08 0.8 4 4.6 0.53 0.53 Phosphoric acid 99%(g) 75 74 59 56 75 75 boric acid (g) 6 6 6 6 6 4 water (ml) 25 25 25 2530 15 WRS3 (g) 15 15 15 15 10 25 SiO₂/P₂O₅ 0.002 0.018 0.158 0.198 0.0180.018 Al₂O₃/SiO₂ 0.53 0.53 0.53 0.53 0.53 0.53 Al₂O₃/P₂O₅ 0.001 0.010.084 0.105 0.01 0.01 P/B 24 23 18 17.6 24 36 Calcium silicate (g) 60 6060 60 60 60 pH of the acid solution <1 <1 <1 <1 <1 <1 initial settingtime (hour) >40 >3 <0.2 <0.2 >20 >40 WRS/P + B 0.01 0.01 0.012 0.0120.006 0.015 The ratio P/B, SiO₂/P₂O₅, Al₂O₃/SiO₂, Al₂O₃/P₂O₅ are weightratio for the acid solution (before addition of the calcium silicateparticles). WRS2 is the amount in gram of water repellent solutionincluding the water present WRS/P + B is the weight ratio between thewater repellent silicon compound (i.e. the active agent present in thesolution) and the sum of phosphorus and boron present in the solution.

TABLE 4 comparative comparative Binder 19 20 21 22 23 24 SiO₂ (g) 0.151.45 7.25 8.7 1 1 Al₂O₃ (g) 0.08 0.8 4 4.6 0.53 0.53 Phosphoric acid 75%(g) 100 98 79 75 100 100 boric acid (g) 6 6 6 6 6 4 water (ml) 0.5 2 911 0 5 WRS1 (g) 15 15 15 15 10 25 SiO₂/P₂O₅ 0.002 0.018 0.158 0.1980.018 0.018 Al₂O₃/SiO₂ 0.53 0.53 0.53 0.53 0.53 0.53 Al₂O₃/P₂O₅ 0.0010.01 0.084 0.105 0.01 0.01 P/B 24 23 18 17.6 24 36 Calcium silicate (g)60 60 60 60 60 60 pH of the acid solution <1 <1 <1 <1 <1 <1 initialsetting time (hour) >40 >3 <0.2 <0.2 >20 >40 WRS/P + B 0.01 0.01 0.0120.012 0.006 0.015 The ratio P/B, SiO₂/P₂O₅, Al₂O₃/SiO₂, Al₂O₃/P₂O₅ areweight ratio for the acid solution (before addition of the calciumsilicate particles). WRS1 is the amount in gram of water repellentsolution including the water present WRS/P + B is the weight ratiobetween the water repellent silicon compound (i.e. the active agentpresent in the solution) and the sum of phosphorus and boron present inthe solution.

TABLE 5 comparative comparative Binder 25 26 27 28 29 30 SiO₂ (g) 0.151.45 7.25 8.7 1 1 Al₂O₃ (g) 0.08 0.8 4 4.6 0.53 0.53 Phosphoric acid 75%(g) 100 98 79 75 100 100 boric acid (g) 6 6 6 6 6 4 water (ml) 0.5 2 911 0 5 WRS2 (g) 15 15 15 15 10 25 SiO₂/P₂O₅ 0.002 0.018 0.158 0.1980.018 0.018 Al₂O₃/SiO₂ 0.53 0.53 0.53 0.53 0.53 0.53 Al₂O₃/P₂O₅ 0.0010.01 0.084 0.105 0.01 0.01 P/B 24 23 18 17.6 24 36 Calcium silicate (g)60 60 60 60 60 60 pH of the acid solution <1 <1 <1 <1 <1 <1 initialsetting time (hour) >40 >3 <0.2 <0.2 >20 >40 WRS/P + B 0.01 0.01 0.0120.012 0.006 0.015 The ratio P/B, SiO₂/P₂O₅, Al₂O₃/SiO₂, Al₂O_(3/)P₂O₅are weight ratio for the acid solution (before addition of the calciumsilicate particles). WRS2 is the amount in gram of water repellentsolution including the water present WRS/P + B is the weight ratiobetween the water repellent silicon compound (i.e. the active agentpresent in the solution) and the sum of phosphorus and boron present inthe solution.

TABLE 6 comparative comparative Binder 31 32 33 34 35 36 SiO₂ (g) 0.151.45 7.25 8.7 1 1 Al₂O₃ (g) 0.08 0.8 4 4.6 0.53 0.53 Phosphoric acid 75%(g) 100 98 79 75 100 100 boric acid (g) 6 6 6 6 6 4 water (ml) 0.5 2 911 0 5 WRS3 (g) 15 15 15 15 10 25 SiO₂/P₂O₅ 0.002 0.018 0.158 0.1980.018 0.018 Al₂O₃/SiO₂ 0.53 0.53 0.53 0.53 0.53 0.53 Al₂O₃/P₂O₅ 0.0010.01 0.084 0.105 0.01 0.01 P/B 24 23 18 17.6 24 36 Calcium silicate (g)60 60 60 60 60 60 pH of the acid solution <1 <1 <1 <1 <1 <1 initialsetting time (hour) >40 >3 <0.2 <0.2 >20 >40 WRS/P + B 0.01 0.01 0.0120.012 0.006 0.015 The ratio P/B, SiO₂/P₂O₅, Al₂O₃/SiO₂, Al₂O₃/P₂O₅ areweight ratio for the acid solution (before addition of the calciumsilicate particles). WRS2 is the amount in gram of water repellentsolution including the water present WRS/P + B is the weight ratiobetween the water repellent silicon compound (i.e. the active agentpresent in the solution) and the sum of phosphorus and boron present inthe solution.

TABLE 7 comparative comparative Binder 37 38 39 40 41 42 SiO₂ (g) 0.151.45 7.25 8.7 1 1 Al₂O₃ (g) 0.08 0.8 4 4.6 0.53 0.53 Phosphoric acid 99%(g) 75 74 59 56 75 75 boric acid (g) 6 6 6 6 6 4 water (ml) 25 25 25 2530 15 SiO₂/P₂O₅ 0.002 0.018 0.158 0.198 0.018 0.018 Al₂O₃/SiO₂ 0.53 0.530.53 0.53 0.53 0.53 Al₂O₃/P₂O₅ 0.001 0.01 0.084 0.105 0.01 0.01 P/B 2423 18 17.6 24 36 Calcium silicate (g) 60 60 60 60 60 60 WRS1 (g) 15 1515 15 10 25 pH of the acid solution <1 <1 <1 <1 <1 <1 initial settingtime (hour) >50 >5 <0.2 <0.2 >30 >50 WRS/P + B 0.01 0.01 0.012 0.0120.006 0.015 The calcium silicate particles were pretreated with the WRS1solution, prior to be added to the acid alumina-boron-silica phosphatesolution. The ratio P/B, SiO₂/P₂O₅, Al₂O₃/SiO₂, Al₂O₃/P₂O₅ are weightratio for the acid solution (before addition of the calcium silicateparticles). WRS1 is the amount in gram of water repellent solutionincluding the water present WRS/P + B is the weight ratio between thewater repellent silicon compound (i.e. the active agent present in thesolution) and the sum of phosphorus and boron present in the solution.

Examples of Compositions of the Invention

The binders n° 1, 7, 11, 12, 17, 18, 24, 30, 35, 41 and 42 which remainliquid for more than 20 hours at room temperature were mixed withvarious additives and/or filler.

The following tables gives the different additives and fillers used,expressed in part by weight, the binder being expressed as dry matter(without water).

TABLE 8 Product n ° 1 2 3 4 5 6 7 8 Binder (dry matter, 1 1 1 1 1 1 1 1part by weight) RHF1 0.1 0.1 0.5 RHF2 0.1 RBCF1 0.2 0.4 0.4 0.4 RBC 0.3CAS 0.2 SF 0.02 0.02 0.05 0.05 0.1 0.1 0.1 0.1 Sf 0.1 0.2 0.2 GF 0.5 1Product n ° 9 10 11 12 13 14 15 16 Binder (dry matter, 1 1 1 1 1 1 1 1part by weight) RHF1 0.1 0.1 0.5 RHF2 0.1 RBCF1 0.2 0.4 0.4 0.4 RBC 0.3CAS 0.2 SF 0.02 0.02 0.05 0.05 0.1 0.1 0.1 0.1 Sf 0.1 0.1 0.1 0.1 0.20.2 GF 0.5 0.5 1 0.2 BF 0.5 1 0.5 0.5 0.5 1 CF 0.5 0.5 0.5 0.2 Product n° 17 18 19 20 21 22 Binder 1 1 1 1 1 1 (part by volume) Additive H₂O₂Silica Aluminum Super Ligno- Quartz (Part by 0.13 Fume powderPlasticizer Sulfonate 0.54 volume) 0.42 0.12 0.15 0.13 Filler Vermi-Straw Fly ash Chip Flax Silica (part by culite 3 parts 0.52 1.22 FiberFlour volume) 0.33 0.75 0.25 Appearance Foam, Low Foam Low Low Heavy ofthe low density Low density density density product density density

For the preparation of said compositions, water can be added forcontrolling the viscosity of the composition, said viscosity beingpreferably maintained as low as possible during the mixing step.

To the compositions of Table 8, one or more further additives or fillerscan be added.

The following table gives possible additives and fillers which can beadded to the compositions of the table 8. Said addition is carried outwhen the composition is sufficient liquid. Possibly some water is addedbefore the addition and/or during the addition of said additives andfillers.

TABLE 10 Examples of possible additive and filler added to one volume ofa composition with a solid content of 25% and 50% by weight AdditiveH₂O₂ Silica Aluminum Super Ligno- Quartz (Part by 0.13 Fume powderPlasticizer Sulfonate 0.54 volume) 0.42 0.12 0.15 0.13 Filler Vermi-Straw Fly ash Chip Flax Silica (part by culite 3 parts 0.52 1.22 FiberFlower volume) 0.33 0.75 0.25 Appearance Foam, Low Foam Low Low Heavy ofthe low density Low density density density product density density

The composition comprising one or more inert fillers are preferablyprepared by premixing at least partly the inert fillers with the calciumsilicate, before using said calcium silicate for the preparation of thebinder. The premix was thus mixed with the acid silica alumina boronphosphate solution.

For accelerating the curing or hardening of the composition, heat wasapplied.

Examples of Coating Operation

A wood board with a thickness of 20 mm has been cut in samples with asize of 200 mm×200 mm. One sample was used as control sample. Saidcontrol sample was dipped in water at 20° C. for 72 hours. The waterabsorption of the control sample was 46% (i.e. the weight of the woodboard was increased by 46% due to the dipping in water, with respect tothe weight of the dry board before its dipping

dry meaning a water content of less than 10% by weight in the board),while the swelling of the product was 37% (i.e. the volume of the samplewas increased by 37% due to the dipping with respect to the volume ofthe dry board—dry meaning a water content of less than 10% by weight),

The samples have been submitted respectively to the following treatment.

Sample 1

Composition 7 of Table 1 has been used just after its preparation forcoating the upper face of sample. The coating after drying had athickness of 2 mm.

After its complete curing, the sample was dipped in water (20° C.) for72 hours. The water absorption was about 25% with a swelling of about8%.

Sample 2

Sample 2 was prepared as disclosed for sample 1, except that aftercoating the front face, the rear face was also coated with a mm thickcoating (composition 7 of Table 1).

After its complete curing of the two coating layer, the sample wasdipped in water (20° C.) for 72 hours. The water absorption was about20% with a swelling of about 6%.

Sample 3

Sample 3 was prepared as disclosed for example 2, except that thereafterthe four lateral faces of the sample were also provided with a coatinglayer (composition 7), said layer having a thickness of about 1- 2 mm.

After complete curing or hardening of the coating layer, the sample wasdipped in water (20° C.) for 72 hours. The water absorption was about14% with a swelling of about 2%.

Sample 4

Sample 4 was prepared as disclosed in example 2, except that the lateralfaces were treated with a water repellent agent (scotchgard™ 3M).

After the complete curing of the two coating layer and of the waterrepellent agent, the sample was dipped in water (20° C.) for 72 hours.The water absorption was about 14% with a swelling of about 0%.

Sample 5

Sample 4 was prepared as disclosed in example 1, except that the lateralfaces were treated with a water repellent agent (scotchgard™ 3M).

After the complete curing of the two coating layer and of the waterrepellent agent, the sample was dipped in water (20° C.) for 72 hours.The water absorption was about 15% with a swelling of about 0-2%.

Sample 6

Sample 6 was prepared as disclosed in example 2, except that before thecoating of the rear and front faces with the composition 7 of Table 1,the lateral faces as well as the edges of the front and rear faces weretreated with a water repellent agent. After the complete curing of thetwo coating layer and of the water repellent agent, the sample wasdipped in water (20° C.) for 72 hours. The water absorption was about14% with a swelling of about 0-2%.

Sample 7

Sample 7 was prepared as disclosed for sample 3, except that thereafterthe hardened layer was further coated with a water repellent agent(scotchgard).

After the complete curing of the two coating layer and of the waterrepellent agent, the sample was dipped in water (20° C.) for 72 hours.The water absorption was about 15% with a swelling of about 0-2%.

Sample 8

Sample 8 was prepared as disclosed for sample 3, except that beforeapplying the hardened layer of composition 7, all the faces of thesample were coated with a water repellent agent (scotchgard).

After the complete curing of the two coating layer and of the waterrepellent agent, the sample was dipped in water (20° C.) for 72 hours.The water absorption was about 15% with a swelling of about 0-2%.

The water absorption and swelling tests was repeated with orientedstrand board. The conclusions of the samples 1 to 8 were maintained.

The composition Product 6 (see table 8) was applied on a face of apolyethylene web of 200 g/m². After hardening of the composition, aflexible film layer was obtained.

The composition 8 was poured so as to produce samples for being testedaccording to the standards BS EN ISO 1716 and ASTMD2015. The maximumamount of heat that the sample can release under highly idealizedconditions was determined in an oxygen bomb calorimeter using adiabaticand isothermal methods. This test determines the maximum total heatrelease of the material after complete combustion, i.e. the differencebetween the gross heat of combustion and the residual heat after 2 hoursof combustion. A gross heat of combustion of 85 KJ/Kg was determined,meaning that the product is considered as an extremely non combustiblematerials (M0).

Mechanical tests were also performed on the sample according to the NBNEN 196-1 standards. It was determined that the product had the followingproperties modulus of rupture 15.5 MPa, compressive strength 30-40 MPa,young's modulus 2200-4500 MPa.

The water capillary porosity was of about 13-14% (ASTM C948-81).

Similarly, the compositions Product n° 10, 13 and 16 (table 8) wereapplied on a face of the polyethylene web with a weight of 200 g/m², soas to prepare a heat resistant film having a total weight varying from250 g/m² up to 700 g/m² (250, 300, 400, 500 and 700 g/m²).

Further coated web and fabrics have been coated with the compositionsProduct n° 6, 10, 13 and 16 (Table 8). The web and fabrics were: basaltfabric with a weight of 100 g/m², 200 g/m², 300 g/m², glass fabric witha weight 100 g/m², 200 g/m² and 300 g/m², glass fiber web with a weightof 250 g/m². The total weight of the coated fabrics or webs were 400g/m² and 500 g/m².

It has been seen that by adding some penetrating agent(s), it waspossible to have a better inflow of the composition into the back sideof the fabrics, mats.

It is also obvious that the coating of the fabric or mat could be madeon both sides, for example by dipping the fabric when moving in a bathcontaining the composition.

It has also been shown that it was possible to have a homogeneouscoating of fibers as such, by dipping glass fibers into a bathcontaining the coating composition, said fibers being thereaftersubmitted to a heat treatment for accelerating the hardening of thecomposition. The so coated fibers, having fire resistance properties,could be rolled onto a mandrel.

Other fibers could also be coated, such as carbon fibers, basalt fibers,nylon fibers, etc.

Fire resistance tests have been carried out on a 40 mm thickpolyurethane panels provided with a glass fiber facing on both sides. PUpanels were further provided on both sides with a coating of thecomposition of the invention, coating having after hardening a thicknessof 0.4 mm (400 μm), said coating being prepared from the compositionsProduct n° 6, 10, 13 and 16 one week prior to the testing.

The testing was carried out according to the EN 13823 single burningtest. The apparatus used for said testing is sited within a testing roomof 3 m long by 3 m wide by 2.4 m high. The room incorporates an openingof dimensions 2150 mm by 1450 mm through which a trolley holding thespecimen is inserted such that it locates within a free-standing frame,positioned adjacent to one wall of the test room. The frame supports arectangular hood through which the fire effluent is drawn by means of afan and a connecting duct system. Two windows in the enclosure enable aviewing of the specimen. The duct system has an internal diameter of 315mm and incorporates a measurement section, positioned at the end of a3125 mm length straight duct section comprising guide vanes for reducingair turbulence at the measurement position. This section is providedwith two K-type thermocouples and one bi-directional probe connected toa differential pressure transducer. The measured temperature and themeasured difference of pressure are used to calculate volume flow withinthe duct. The air flow rate was set at 0.6 m³/s prior to the start ofthe test.

The gas effluent is also analyzed through a paramagnetic oxygenanalyser, enabling to calculate continuously the rate of heat release bymeans of the oxygen consumption method. The obscuration of the lightcaused by the smoke in the fire effluent passing through the exhaustduct is determined by a white light lamp and a photocell system.

The single burning item specimen consists of two walls mounted into theaperture in the specimen trolley, such that they form a vertical 90°corner. The dimension of the walls are 1.5 high by 0.5 m long, and 1.5 mhigh by 1.0 m long.

The trolley comprises a triangular propane sand burner, positioned inthe base of the corner formed by the specimen. The burner is distantfrom the wall by 40 mm between the edge of the burner and the lower edgeof the specimen. Said burner has an output of 30 kW.

The results of said tests are:

a Fire Growth Rate Index FIGRA (W/s) of less than 150 instead of a valueof more than 1500 for traditional fire resistant product.

-a THR600s (MJ), i.e. the Total Heat Release over the first 10 minutesafter primary burner ignition: about 4 instead of more than 6 fortraditional fire resistant product.

SMOGRA or the smoke growth rate index (m²/s²) of less than about 20instead of more than 250 for traditional fire resistant product.

TSP600s or the Total Smoke Production over the first 10 minutes afterprimary burner operation.(m²) of less than 6 instead of more than 80 fortraditional fire resistant product

no flaming droplets/particles within 600s

The compositions Product n° 6, 10, 13 and 16 have been used forpreparing matrix samples for testing procedure. It appears that thesamples had gross heat of combustion is lower than 100 kJ/kg. Saidcompositions when mixed with fibers could enable to prepare productshaving a modulus of rupture of more than about 15 MPa, a compressionmodulus of more than 90 MPa and an Young modulus of more than 11000 MPa.Other fibers could also be coated, such as carbon fibers, basalt fibers,nylon fibers, etc.

1. An inorganic binder having calcium silicate sites which are connectedthe one with the other by alumina-silica phosphate bonds, whereby atleast a portion of said alumina-silica phosphate bonds arealumina-boron-silica phosphate bonds, the calcium silicate sites actingas cross-linking sites for the alumina-silica phosphate bonds, wherebysaid alumina-silicate phosphate bonds have: a weight ratio Al₂O₃/SiO₂ranging from 0.3:1 to 10:1, a weight ratio Al₂O₃/P₂O₅ ranging from0.0005 to 0.04, and a weight ratio P/B ranging from 20:1 to 100:1, andwhereby the inorganic binder further comprises a silicon containingcompound selected from the group consisting of waterproof siliconcompounds, water repellent silicon compounds and mixture thereof, theweight ratio of said silicon containing/P+B being comprised between1:5000 and 1:10, and whereby at least a portion of the calcium silicatesites are at least partly provided with a layer of said siliconcontaining compound.
 2. The binder of claim 1, in which substantiallyall alumina-silica sites are bound the one to the other byalumina-boron-silica phosphate bonds.
 3. The binder of claim 1, in whichthe weight ratio calcium silicate site/SiO₂ present in thealumina-silica phosphate bonds is comprised between 10 and
 200. 4. Thebinder of claim 1, in which the calcium silicate sites are calcium metasilicate sites having a substantially acicular nature with alength/diameter ratio from 2/1 to 50/1 the calcium meta silicate siteshaving advantageously an average length from 10 μm to 10 mm.
 5. Thebinder of claim 1, in which the weight ratio calcium silicatesites/alumina-silica-boron phosphate bonds is comprised between 0.1 and1.1, and in which calcium silicate sites are at least partly providedwith a layer of said silicon containing compound.
 6. (canceled) 7.(canceled)
 8. (canceled)
 9. A composition comprising at least: (a) aninorganic binder having calcium silicate sites which are connected theone with the other by alumina-silica phosphate bonds, whereby at least aportion of said alumina-silica phosphate bonds are alumina-boron-silicaphosphate bonds, the calcium silicate sites acting as cross-linkingsites for the alumina-silica phosphate bonds, whereby saidalumina-silicate phosphate bonds have: a weight ratio Al₂O₃/SiO₂,ranging from 0.3:1 to 10:1, a weight ratio Al₂O₃/P₂O₅ ranging from0.0005 to 0.04, and a weight ratio P/B ranging from 20:1 to 100:1, andwhereby the inorganic binder further comprises a silicon containingcompound selected from the group consisting of waterproof siliconcompounds, water repellent silicon compounds and mixture thereof, theweight ratio said silicon containing compound/P+B being comprisedbetween 1:5000 and 1:10, and whereby at least a portion of the calciumsilicate sites are at least partly provided with a layer of said siliconcontaining compound, and (b) a silicon containing filler.
 10. Thecomposition of claim 9, in which the silicon containing filler comprisessilicon containing fibers with a weight average length comprised between25 μm and 300 μm.
 11. (canceled)
 12. (canceled)
 13. The composition ofclaim 9, in which the silicon containing filler comprises siliconcontaining fibers, whereby after hardening and removal of free water ofthe composition, the composition comprises from 1% up to 85% by weightsilicon containing fibers with a length of less than 500 μm, which aresubstantially not reactive with the binder.
 14. The composition of claim9, which further comprises silica flour with a particle size comprisedbetween 5 and 60 μm, the weight content of said silica flour in thecomposition after its hardening and after removal of the possible freewater being comprised between 1 and 10%.
 15. (canceled)
 16. Thecomposition of claim 9, which further comprises crystallized aluminasilicate particles which are substantially not reactive with the binderand which have a weight average particle size comprised between 5 and100 μm, the weight content of said substantially non reactivecrystallized alumina silicate in the composition after its hardening andafter removal of the possible free water being comprised between 1 and10%.
 17. A product comprising a support having at least one face atleast partly coated with a composition comprising at least: (a) aninorganic binder having calcium silicate sites which are connected theone with the other by alumina-silica phosphate bonds, whereby at least aportion of said alumina-silica phosphate bonds are alumina-boron-silicaphosphate bonds, the calcium silicate sites acting as cross-linkingsites for the alumina-silica phosphate bonds, whereby saidalumina-silicate phosphate bonds have: a weight ratio Al₂O₃/SiO₂ rangingfrom 0.3:1 to 10:1, a weight ratio Al₂O₃/P₂O₅ ranging from 0.0005 to0.04, and a weight ratio P/B ranging from 20:1 to 100:1, and whereby theinorganic binder further comprises a silicon containing compoundselected from the group consisting of waterproof silicon compounds,water repellent silicon compounds and mixture thereof, the weight ratiosaid silicon containing compound/P+B being comprised between 1:5000 and1:10, and whereby at least a portion of the calcium silicate sites areat least partly provided with a layer of said silicon containingcompound, and (b) a silicon containing filler.
 18. (canceled) 19.(canceled)
 20. The product of claim 17, in which the support is a glassfabric with a weight from 50 g/m² to 500 g/m², at least one face thereofbeing at least partly coated with a layer of the said composition, saidlayer having an average thickness comprised between 50 μm and 250 μm.21. A process for the preparation of an inorganic binder having calciumsilicate sites which are connected the one with the other byalumina-silica phosphate bonds, the calcium silicate sites acting ascross-linking sites for the alumina-silica phosphate bonds with a weightratio Al₂O₃/SiO₂ ranging from 0.3:1 and 10:1, * in which water insolublecalcium silicate particles partly coated with a layer of a siliconcontaining compound selected from the group consisting of waterproofsilicon containing compounds, water repellent silicon containingcompounds or and mixtures thereof, are mixed with an acid alumina-silicaphosphate solution comprising boric acid and a silicon containingcompound selected from the group consisting of waterproof siliconcontaining compounds, water repellent silicon containing compounds andmixtures thereof, at a temperature lower than 70° C., said acidalumina-silica phosphate solution comprising solubilized SiO₂ and havinga pH of less than 2, said acid alumina-silica phosphate solution having:a weight ratio Al₂O₃/SiO₂ ranging from 0.3:1 and 10:1, a weight ratioAl₂O₃/P₂O₅ ranging from 0.0005 to 0.04, and a weight boron content suchthat the weight ration P/B is comprised from 20:1 to 100:1, and saidacid alumina-silica phosphate comprising an amount of said siliconcontaining compound such that the weight ratio said waterproof and/orwater repellent silicon containing compound/P+B is comprised between1:500 and 1:75, and whereby at least a portion of the calcium silicatesites are at least partly provided with a layer of said siliconcontaining compound.
 22. The process of claim 21, in which at least onefiller is added to a composition selected from the group consisting ofthe binder before its hardening, the acid alumina-silica phosphatesolution and the calcium silicate to be reacted with the acidalumina-silica-phosphate solution.
 23. (canceled)
 24. The process ofclaim 21, in which the hardening of the binder is carried out at atemperature comprised between 0° C. and 50° C.
 25. The process of claim21, in which the binder is hardened under pressure.
 26. The process ofclaim 21, in which the amount of calcium silicate added to the acidsilica alumina phosphate solution is such that the weight ratio calciumsilicate/SiO₂ present in the acid solution is comprised between 1 and500.
 27. The process of claim 21, in which the acid silica aluminaphosphate solution is prepared by mixing a silica-alumina mixture withan acid mixture consisting substantially only of phosphoric acid andboric acid, with a weight ratio P/B ranging from 20:1 to 100:1.
 28. Theprocess of claim 21, in which the acid silica alumina phosphate solutionis prepared by mixing a silica-alumina mixture with a boron salt and anacid selected from the group consisting of phosphoric acid and a mix ofphosphoric acid and boric acid, whereby the weight ratio P/B of the soprepared acid alumina phosphate solution ranges from 20:1 to 100:1. 29.The process of claim 21, in which the acid silica alumina phosphatesolution is prepared by mixing silica particles with an acid consistingsubstantially only of phosphoric acid or of a mixture of phosphoric acidand boric acid, and by mixing thereafter said particles to the acidsilica containing solution alumina particles.
 30. The binder of claim 1,whereby the binder is the reaction product obtained by reacting an acidalumina-silica-boron phosphate solution having a pH of less than 2, saidacid alumina-silica phosphate solution having: a weight ratio Al₂O₃/SiO₂ranging from 0.3:1 and 10:1, a weight ratio Al₂O₃/P₂O₅ ranging from0.0005 to 0.04, and a weight boron content such that the weight rationP/B is comprised from 20:1 to 100:1, with an amount of calcium silicateparticles such that the weight ratio calcium silicate site/SiO₂ presentin the alumina-silica phosphate bonds is comprised between 10 and 200,in presence of an amount of a silicon containing compound selected fromthe group consisting of waterproof silicon containing compounds, waterrepellent silicon containing compounds and mixture thereof, such thatthe weight ratio said silicon containing compound/P+B being comprisedbetween 1:5000 and 1:10.
 31. The composition of claim 9, whereby thebinder is the reaction product obtained by reacting an acidalumina-silica-boron phosphate solution having a pH of less than 2, saidacid alumina-silica phosphate solution having: a weight ratio Al₂O₃/SiO₂ranging from 0.3:1 and 10:1, a weight ratio Al₂O₃/P₂O₅ ranging from0.0005 to 0.04, and a weight boron content such that the weight rationP/B is comprised from 20:1 to 100:1, with an amount of calcium silicateparticles such that the weight ratio calcium silicate site/SiO₂ presentin the alumina-silica phosphate bonds is comprised [between 1 and 1000,advantageously] between 10 and 200, in presence of an amount of asilicon containing compound selected from the group consisting ofwaterproof silicon containing compounds, water repellent siliconcontaining compounds and mixture thereof, such that the weight ratiosaid silicon containing compound/P+B being comprised between 1:5000 and1:10, whereby said reaction is carried out in presence of at least onesilicon containing filler.
 32. The binder of claim 1, in which thealumina-silicate phosphate bonds have: a weight ratio Al₂O₃/SiO₂ rangingfrom 0.4:1 to 6:1, a weight ratio Al₂O₃/P₂O₅ ranging from 0.0008 to0.03, and a weight ratio P/B ranging from 21:1 to 50:1, and whereby theinorganic binder further comprises a silicon containing compoundselected from the group consisting of waterproof silicon compounds,water repellent silicon compounds and mixture thereof, the weight ratiosaid silicon containing compound/P+B being comprised between 1:1000 and1:25, and whereby at least a portion of the calcium silicate sites areat least partly provided with a layer of said silicon containingcompound.